Blind rivets that are provided with a metal rivet main body having a sleeve and a flange on one end of the sleeve, a head and a metal mandrel having a shaft extending from the head, are well known. An advantage of a blind rivet is that it can connect to a plurality of panels by working from just one side.
A user would expect sufficient sealing and a high degree of water tightness between the rivet and the base body such as a panel (the attached member) after the blind rivet is fastened.
There are two types of blind rivets. One is a sealed type in which the head of the mandrel, which causes the rivet main body to change when fastening, is set in the middle of the rivet, and the remaining head of the mandrel is not exposed to the blind side opposite the working side after fastening to the base body. The other is an open type in which the head of the mandrel sticks out of the rivet, and the remaining head of the mandrel is exposed to the blind side after fastening to the base body.
The open type of blind rivet is not sufficiently watertight; it is easy for liquid to seep between the rivet main body and the remaining head of the mandrel because the remaining head of the mandrel is exposed after fastening. The sealed type of blind rivet has excellent water tightness; after fastening, it is more difficult for liquid to seep compared to the valved type, because only the rivet main body is exposed to the blind side after fastening.
Kokai 2012-9288 discloses a sealing device consisting of a sealed type blind rivet, which seals the opening of a sealed rechargeable battery, and a resinous sleeve. The sealing device is provided with a metal core having a shaft and a large-diameter part, a flange bottomed metallic cylindrical member and a flange bottomed resinous sleeve into which part of the metallic cylindrical member is inserted from the opening side. When the metal core is pulled out of the metallic cylindrical member, the metallic cylindrical member is modified by the large-diameter part expanding in a radial direction. The resinous sleeve, expanding in a radial direction by the change of the metallic cylindrical member, seals the opening of the sealed rechargeable battery.
The sealing device of Kokai 2012-9288, while maintaining cohesion of the resinous sleeve and the battery contents, is able to hold a hermetic seal of the battery. However, because it uses a bottomed resinous sleeve besides a blind rivet, the number of parts will be many, and cost will be high.
Kokai 2012-145167 discloses a shield type blind rivet consisting of a mandrel and a rivet. The mandrel has a large diameter head on one end in the shape of a round rod. The rivet has a rivet main body in which one end is closed in the shape of a cylinder, and on the other end of the rivet main body, there is a flange. The rivet has the mandrel set so that it cannot come out by sealing the head when positioning it on the closed end. The rivet main body has a taper whose exterior form gets gradually smaller toward one end from the part connecting with the flange.
Because it has a taper, in the blind rivet of Kokai 2012-145167, the area of overlap to the hole for a plate rivet and the rivet main body becomes smaller and a high degree of water tightness can be attained.
However, this taper is provided with a small angle on the rivet main body, because it is assumed that it will overlap the hole for the plate rivet; if the variability of the inner diameter of the hole for the plate rivet is great, it is easy in the blind rivet of Kokai 2012-145167 for a part of the hole for the plate rivet not to overlap, and a high degree of water tightness cannot be attained at all.
Kokai 2002-529663 discloses a blind rivet consisting of a head, an outer part in which a bottomed axial hole forms a shank extending from the head, a stem head and an inner part that has a stem disposed in the axial hole. The shank has a shank fastening part with a taper.
The blind rivet of Kokai 2002-529663 has a problem with insufficient filling of the hole below the head, as the shank is actually mutually dependent on the work piece hole.
However, the blind rivet of Patent Reference 3 is of the open type and, because the remainder part of the mandrel is exposed to the blind side, it is easy for leaking to occur between the rivet main body and the remainder part of the mandrel, so insufficient water tightness is an inherent problem with the open type.
For this reason, we are seeking a blind rivet having a sufficient seal in the single blind rivet and a high degree of water tightness without the use of a washer or an O-ring.